Method and user equipment for transmitting uplink signal and prose signal

ABSTRACT

One disclosure of the present specification provides a method for simultaneously transmitting, by user equipment (UE), a cellular uplink signal and a proximity service (ProSe) signal. The method may comprise a step of determining the total transmission power P CMAX  of the cellular uplink signal and the ProSe signal. Here, the total transmission power P CMAX  may satisfy P CMAX_L ≤P CMAX ≤P CMAX_H . At this time, P CMAX_L  may be a lower limit value and P CMAX_H  may be an upper limit value. The cellular uplink signal is transmitted in a subframe n, the ProSe signal is transmitted in a subframe m, and subframe n may be considered as a reference subframe if subframe n and subframe m are time asynchronous.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is the National Stage filing under 35 U.S.C. 371 ofInternational Application No. PCT/KR2016/010260, filed on Sep. 12, 2016,which claims the benefit of U.S. Provisional Application No. 62/220,246,filed on Sep. 18, 2015 and 62/236,986, filed on Oct. 5, 2015, thecontents of which are all hereby incorporated by reference herein intheir entirety.

BACKGROUND OF THE INVENTION Field of the Invention

The present invention relates to mobile communication.

Related Art

3^(rd) generation partnership project (3GPP) long term evolution (LTE)evolved from a universal mobile telecommunications system (UMTS) isintroduced as the 3GPP release 8. The 3GPP LTE uses orthogonal frequencydivision multiple access (OFDMA) in a downlink, and uses singlecarrier-frequency division multiple access (SC-FDMA) in an uplink.

Development of 3GPP LTE-Advanced (LTE-A) which is an evolution of the3GPP LTE has been completed in recent years. According to the LTE-A, acarrier aggregation (CA) technology is presented, which aggregates anduses multiple bands into one.

A frequency which can be used for LTE/LTE-A, that is, a carrier, isdefined in 3GPP by considering radio wave situations of variouscountries.

With increasing demands for social networking services (SNSs) fromusers, communication between user equipments (UEs) physically adjacent,that is, device-to-device (D2D) communication, is required.

However, when a D2D signal to an adjacent UE and a signal to a basestation (BS) are simultaneously transmitted, a UE has transmission powerdetermined depending on the power class of the UE, and thus it isnecessary to divide the transmission power to transmit the signals.Therefore, it is needed to study a method for a UE to transmit all datasignals without exceeding maximum transmission power according to thepower class.

SUMMARY OF THE INVENTION

Accordingly, a disclosure of the present specification has been made inan effort to solve the aforementioned problem.

In order to achieve the above-described technical object of the presentinvention, a disclosure of this specification provides a method forsimultaneously transmitting a cellular uplink signal and a proximityservice (ProSe) signal. The method may be performed by a user equipment(UE) and comprise: determining a total transmission power P_(CMAX) forthe cellular uplink signal and the ProSe signal. The total transmissionpower P_(CMAX) may satisfies P_(CMAX_L)≤P_(CMAX)≤P_(CMAX_H). TheP_(CMAX_L) is a lower bound and P_(CMAX_H) may be an upper bound. If thecellular uplink signal is transmitted on subframe n, if the ProSe signalis transmitted on subframe m and if the subframe n is asynchronous withthe subframe m, the subframe n may be taken as a reference. If thetransmission of the uplink signal leads the transmission of the ProSesignal, the upper bound P_(CMAX_H) may be determined in consideration ofsubframe pairs of (n, m) and (n, m−1).

The upper bound P_(CMAX_H) is

determined by a following equation:P _(CMAX_H)=MAX {P _(CMAX_H)(n,m−1),P _(CMAX_H)(n,m)}.

The cellular uplink signal may be transmitted to a base station and theProSe signal may be transmitted to an adjacent other UE.

A carrier for transmitting the cellular uplink signal may be differentfrom a carrier for transmitting the ProSe signal.

A carrier for transmitting the cellular uplink signal and a carrier fortransmitting the ProSe signal may correspond to an inter-band carrieraggregation.

In order to achieve the above-described technical object of the presentinvention, a disclosure of this specification also provides a userequipment (UE) for simultaneously transmitting a cellular uplink signaland a proximity service (ProSe) signal. The UE may comprise: a processorconfigured to determine a total transmission power P_(CMAX) for thecellular uplink signal and the ProSe signal. The total transmissionpower P_(CMAX) may satisfies P_(CMAX_L)≤P_(CMAX)≤P_(CMAX_H). TheP_(CMAX_L) is a lower bound and P_(CMAX_H) may be an upper bound. If thecellular uplink signal is transmitted on subframe n, if the ProSe signalis transmitted on subframe m and if the subframe n is asynchronous withthe subframe m, the subframe n may be taken as a reference. If thetransmission of the uplink signal leads the transmission of the ProSesignal, the upper bound P_(CMAX_H) may be determined in consideration ofsubframe pairs of (n, m) and (n, m−1).

Accordingly, a disclosure of the present specification has been made inan effort to solve the aforementioned problem.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates a wireless communication system.

FIG. 2 illustrates the architecture of a radio frame according tofrequency division duplex (FDD) of 3rd generation partnership project(3GPP) long term evolution (LTE).

FIG. 3 illustrates an example resource grid for one uplink or downlinkslot in 3GPP LTE.

FIG. 4 illustrates the architecture of a downlink subframe.

FIG. 5 illustrates the architecture of an uplink subframe in 3GPP LTE.

FIGS. 6A and 6B are conceptual views illustrating intra-band carrieraggregation (CA).

FIGS. 7A and 7B are conceptual views illustrating inter-band carrieraggregation (CA).

FIG. 8 illustrates a method for limiting the transmission power of a UE.

FIG. 9 shows a heterogeneous network environment, in which a macrocelland a small cell coexist, as a potential next-generation wirelesscommunication system.

FIG. 10a illustrates the concept of D2D communication that is expectedto be introduced in a next-generation communication system.

FIG. 10b illustrates an example of transmitting a discovery signal forD2D communication.

FIG. 11a illustrates an example in which a band used for D2Dcommunication is different from an LTE/LTE-A band used for cellularcommunication, and FIG. 11b illustrates an RF structure.

FIGS. 12a to 12c illustrate bands for D2D transmission/reception and forWAN transmission/reception.

FIG. 13 illustrates that time synchronization between WAN transmissionand D2D transmission is achieved to a certain extent.

FIG. 14a illustrates subframes for WAN transmission and D2D transmissionthrough a resource based on a mode other than mode I in the synchronousenvironment of FIG. 13, and FIG. 14b illustrates subframes for WANtransmission and D2D transmission through a resource based on mode I inthe synchronous environment of FIG. 13.

FIG. 15 illustrates WAN transmission power per slot for a UE in CC1 andD2D transmission power per slot for the UE in CC2.

FIG. 16 illustrates WAN transmission power per slot for a UE in CC1 andD2D transmission power per slot for the UE in CC2 in the situation ofFIG. 14 a.

FIG. 17 illustrates WAN transmission power per slot for a UE in CC1 andD2D transmission power per slot for the UE in CC2 in the situation ofFIG. 14 b.

FIG. 18 illustrates that time synchronization between WAN transmissionand D2D transmission is not achieved,

FIGS. 19a to 19d illustrate examples of WAN transmission time and D2Dtransmission time in the asynchronous environment of FIG. 18.

FIG. 20 illustrates transmission power per slot in the case where D2Dtransmission time leads WAN transmission time in the asynchronousenvironment of FIG. 18.

FIG. 21 illustrates transmission power per slot in the case where WANtransmission time leads D2D transmission time in the asynchronousenvironment of FIG. 18.

FIG. 22 is a block diagram illustrating a wireless communication systemto implement the present disclosure.

DESCRIPTION OF EXEMPLARY EMBODIMENTS

Hereinafter, based on 3rd Generation Partnership Project (3GPP) longterm evolution (LTE) or 3GPP LTE-advanced (LTE-A), the present inventionwill be applied. This is just an example, and the present invention maybe applied to various wireless communication systems. Hereinafter, LTEincludes LTE and/or LTE-A.

The technical terms used herein are used to merely describe specificembodiments and should not be construed as limiting the presentinvention. Further, the technical terms used herein should be, unlessdefined otherwise, interpreted as having meanings generally understoodby those skilled in the art but not too broadly or too narrowly.Further, the technical terms used herein, which are determined not toexactly represent the spirit of the invention, should be replaced by orunderstood by such technical terms as being able to be exactlyunderstood by those skilled in the art. Further, the general terms usedherein should be interpreted in the context as defined in thedictionary, but not in an excessively narrowed manner.

The expression of the singular number in the specification includes themeaning of the plural number unless the meaning of the singular numberis definitely different from that of the plural number in the context.In the following description, the term ‘include’ or ‘have’ may representthe existence of a feature, a number, a step, an operation, a component,a part or the combination thereof described in the specification, andmay not exclude the existence or addition of another feature, anothernumber, another step, another operation, another component, another partor the combination thereof.

The terms ‘first’ and ‘second’ are used for the purpose of explanationabout various components, and the components are not limited to theterms ‘first’ and ‘second’. The terms ‘first’ and ‘second’ are only usedto distinguish one component from another component. For example, afirst component may be named as a second component without deviatingfrom the scope of the present invention.

It will be understood that when an element or layer is referred to asbeing “connected to” or “coupled to” another element or layer, it can bedirectly connected or coupled to the other element or layer orintervening elements or layers may be present. In contrast, when anelement is referred to as being “directly connected to” or “directlycoupled to” another element or layer, there are no intervening elementsor layers present.

Hereinafter, exemplary embodiments of the present invention will bedescribed in greater detail with reference to the accompanying drawings.In describing the present invention, for ease of understanding, the samereference numerals are used to denote the same components throughout thedrawings, and repetitive description on the same components will beomitted. Detailed description on well-known arts which are determined tomake the gist of the invention unclear will be omitted. The accompanyingdrawings are provided to merely make the spirit of the invention readilyunderstood, but not should be intended to be limiting of the invention.It should be understood that the spirit of the invention may be expandedto its modifications, replacements or equivalents in addition to what isshown in the drawings.

As used herein, ‘base station’ generally refers to a fixed station thatcommunicates with a wireless device and may be denoted by other termssuch as eNB (evolved-NodeB), BTS (base transceiver system), or accesspoint.

As used herein, user equipment (UE) may be stationary or mobile, and maybe denoted by other terms such as device, wireless device, terminal,MS(mobile station), UT(user terminal), SS(subscriber station), MT(mobileterminal) and etc.

FIG. 1 illustrates a wireless communication system.

Referring to FIG. 1, the wireless communication system includes at leastone base station (BS) 20. Respective BSs 20 provide a communicationservice to particular geographical areas 20 a, 20 b, and 20 c (which aregenerally called cells).

The UE generally belongs to one cell and the cell to which the terminalbelong is referred to as a serving cell. A base station that providesthe communication service to the serving cell is referred to as aserving BS. Since the wireless communication system is a cellularsystem, another cell that neighbors to the serving cell is present.Another cell which neighbors to the serving cell is referred to aneighbor cell. A base station that provides the communication service tothe neighbor cell is referred to as a neighbor BS. The serving cell andthe neighbor cell are relatively decided based on the UE.

Hereinafter, a downlink means communication from the base station 20 tothe terminal 10 and an uplink means communication from the terminal 10to the base station 20. In the downlink, a transmitter may be a part ofthe base station 20 and a receiver may be a part of the terminal 10. Inthe uplink, the transmitter may be a part of the terminal 10 and thereceiver may be a part of the base station 20.

Hereinafter, the LTE system will be described in detail.

FIG. 2 shows a downlink radio frame structure according to FDD of 3rdgeneration partnership project (3GPP) long term evolution (LTE).

The radio frame of FIG. 2 may be found in the section 5 of 3GPP TS36.211 V10.4.0 (2011-12) “Evolved Universal Terrestrial Radio Access(E-UTRA); Physical Channels and Modulation (Release 10)”.

Referring to FIG. 2, the radio frame consists of 10 subframes. Onesubframe consists of two slots. Slots included in the radio frame arenumbered with slot numbers 0 to 19. A time required to transmit onesubframe is defined as a transmission time interval (TTI). The TTI maybe a scheduling unit for data transmission. For example, one radio framemay have a length of 10 milliseconds (ms), one subframe may have alength of 1 ms, and one slot may have a length of 0.5 ms.

The structure of the radio frame is for exemplary purposes only, andthus the number of subframes included in the radio frame or the numberof slots included in the subframe may change variously.

Meanwhile, one slot may include a plurality of OFDM symbols. The numberof OFDM symbols included in one slot may vary depending on a cyclicprefix (CP).

FIG. 3 illustrates an example resource grid for one uplink or downlinkslot in 3GPP LTE.

Referring to FIG. 3, the uplink slot includes a plurality of OFDM(orthogonal frequency division multiplexing) symbols in the time domainand N_(RB) resource blocks (RBs) in the frequency domain. For example,in the LTE system, the number of resource blocks (RBs), i.e., N_(RB),may be one from 6 to 110.

Resource block (RB) is a resource allocation unit and includes aplurality of sub-carriers in one slot. For example, if one slot includesseven OFDM symbols in the time domain and the resource block includes 12sub-carriers in the frequency domain, one resource block may include7×12 resource elements (REs).

Meanwhile, the number of sub-carriers in one OFDM symbol may be one of128, 256, 512, 1024, 1536, and 2048.

In 3GPP LTE, the resource grid for one uplink slot shown in FIG. 4 mayalso apply to the resource grid for the downlink slot.

FIG. 4 illustrates the architecture of a downlink sub-frame.

In FIG. 4, assuming the normal CP, one slot includes seven OFDM symbols,by way of example.

The DL (downlink) sub-frame is split into a control region and a dataregion in the time domain. The control region includes up to first threeOFDM symbols in the first slot of the sub-frame. However, the number ofOFDM symbols included in the control region may be changed. A PDCCH(physical downlink control channel) and other control channels areallocated to the control region, and a PDSCH is allocated to the dataregion.

The physical channels in 3GPP LTE may be classified into data channelssuch as PDSCH (physical downlink shared channel) and PUSCH (physicaluplink shared channel) and control channels such as PDCCH (physicaldownlink control channel), PCFICH (physical control format indicatorchannel), PHICH (physical hybrid-ARQ indicator channel) and PUCCH(physical uplink control channel).

The PCFICH transmitted in the first OFDM symbol of the sub-frame carriesCIF (control format indicator) regarding the number (i.e., size of thecontrol region) of OFDM symbols used for transmission of controlchannels in the sub-frame. The wireless device first receives the CIF onthe PCFICH and then monitors the PDCCH.

Unlike the PDCCH, the PCFICH is transmitted through a fixed PCFICHresource in the sub-frame without using blind decoding. The PHICHcarries an ACK (positive-acknowledgement)/NACK(negative-acknowledgement) signal for a UL HARQ (hybrid automatic repeatrequest). The ACK/NACK signal for UL (uplink) data on the PUSCHtransmitted by the wireless device is sent on the PHICH.

The PBCH (physical broadcast channel) is transmitted in the first fourOFDM symbols in the second slot of the first sub-frame of the radioframe. The PBCH carries system information necessary for the wirelessdevice to communicate with the base station, and the system informationtransmitted through the PBCH is denoted MIB (master information block).In comparison, system information transmitted on the PDSCH indicated bythe PDCCH is denoted SIB (system information block).

The PDCCH may carry activation of VoIP (voice over internet protocol)and a set of transmission power control commands for individual UEs insome UE group, resource allocation of an upper layer control messagesuch as a random access response transmitted on the PDSCH, systeminformation on DL-SCH, paging information on PCH, resource allocationinformation of UL-SCH (uplink shared channel), and resource allocationand transmission format of DL-SCH (downlink-shared channel). A pluralityof PDCCHs may be sent in the control region, and the terminal maymonitor the plurality of PDCCHs. The PDCCH is transmitted on one CCE(control channel element) or aggregation of some consecutive CCEs. TheCCE is a logical allocation unit used for providing a coding rate perradio channel's state to the PDCCH. The CCE corresponds to a pluralityof resource element groups. Depending on the relationship between thenumber of CCEs and coding rates provided by the CCEs, the format of thePDCCH and the possible number of PDCCHs are determined.

The control information transmitted through the PDCCH is denoteddownlink control information (DCI). The DCI may include resourceallocation of PDSCH (this is also referred to as DL (downlink) grant),resource allocation of PUSCH (this is also referred to as UL (uplink)grant), a set of transmission power control commands for individual UEsin some UE group, and/or activation of VoIP (Voice over InternetProtocol).

The base station determines a PDCCH format according to the DCI to besent to the terminal and adds a CRC (cyclic redundancy check) to controlinformation. The CRC is masked with a unique identifier (RNTI; radionetwork temporary identifier) depending on the owner or purpose of thePDCCH. In case the PDCCH is for a specific terminal, the terminal'sunique identifier, such as C-RNTI (cell-RNTI), may be masked to the CRC.Or, if the PDCCH is for a paging message, a paging indicator, forexample, P-RNTI (paging-RNTI) may be masked to the CRC. If the PDCCH isfor a system information block (SIB), a system information identifier,SI-RNTI (system information-RNTI), may be masked to the CRC. In order toindicate a random access response that is a response to the terminal'stransmission of a random access preamble, an RA-RNTI (randomaccess-RNTI) may be masked to the CRC.

In 3GPP LTE, blind decoding is used for detecting a PDCCH. The blinddecoding is a scheme of identifying whether a PDCCH is its own controlchannel by demasking a desired identifier to the CRC (cyclic redundancycheck) of a received PDCCH (this is referred to as candidate PDCCH) andchecking a CRC error. The base station determines a PDCCH formataccording to the DCI to be sent to the wireless device, then adds a CRCto the DCI, and masks a unique identifier (this is referred to as RNTI(radio network temporary identifier) to the CRC depending on the owneror purpose of the PDCCH.

The uplink channels include a PUSCH, a PUCCH, an SRS (Sounding ReferenceSignal), and a PRACH (physical random access channel).

FIG. 5 illustrates the architecture of an uplink sub-frame in 3GPP LTE.

Referring to FIG. 5, the uplink sub-frame may be separated into acontrol region and a data region in the frequency domain. The controlregion is assigned a PUCCH (physical uplink control channel) fortransmission of uplink control information. The data region is assigneda PUSCH (physical uplink shared channel) for transmission of data (insome cases, control information may also be transmitted).

The PUCCH for one terminal is assigned in resource block (RB) pair inthe subframe. The resource blocks in the resource block pair take updifferent sub-carriers in each of the first and second slots. Thefrequency occupied by the resource blocks in the resource block pairassigned to the PUCCH is varied with respect to a slot boundary. This isreferred to as the RB pair assigned to the PUCCH having beenfrequency-hopped at the slot boundary.

The terminal may obtain a frequency diversity gain by transmittinguplink control information through different sub-carriers over time. mis a location index that indicates a logical frequency domain locationof a resource block pair assigned to the PUCCH in the sub-frame.

The uplink control information transmitted on the PUCCH includes an HARQ(hybrid automatic repeat request), an ACK (acknowledgement)/NACK(non-acknowledgement), a CQI (channel quality indicator) indicating adownlink channel state, and an SR (scheduling request) that is an uplinkradio resource allocation request.

The PUSCH is mapped with a UL-SCH that is a transport channel. Theuplink data transmitted on the PUSCH may be a transport block that is adata block for the UL-SCH transmitted for the TTI. The transport blockmay be user information. Or, the uplink data may be multiplexed data.The multiplexed data may be data obtained by multiplexing the transportblock for the UL-SCH and control information. For example, the controlinformation multiplexed with the data may include a CQI, a PMI(precoding matrix indicator), an HARQ, and an RI (rank indicator). Or,the uplink data may consist only of control information.

<Carrier Aggregation: CA>

Hereinafter, a carrier aggregation system will be described.

The carrier aggregation (CA) system means aggregating multiple componentcarriers (CCs). By the carrier aggregation, the existing meaning of thecell is changed. According to the carrier aggregation, the cell may meana combination of a downlink component carrier and an uplink componentcarrier or a single downlink component carrier.

Further, in the carrier aggregation, the cell may be divided into aprimary cell, secondary cell, and a serving cell. The primary cell meansa cell that operates at a primary frequency and means a cell in whichthe UE performs an initial connection establishment procedure or aconnection reestablishment procedure with the base station or a cellindicated by the primary cell during a handover procedure. The secondarycell means a cell that operates at a secondary frequency and once an RRCconnection is established, the secondary cell is configured and is usedto provide an additional radio resource.

The carrier aggregation system may be divided into a continuous carrieraggregation system in which aggregated carriers are contiguous and anon-contiguous carrier aggregation system in which the aggregatedcarriers are separated from each other. Hereinafter, when the contiguousand non-contiguous carrier systems are just called the carrieraggregation system, it should be construed that the carrier aggregationsystem includes both a case in which the component carriers arecontiguous and a case in which the component carriers arenon-contiguous. The number of component carriers aggregated between thedownlink and the uplink may be differently set. A case in which thenumber of downlink CCs and the number of uplink CCs are the same as eachother is referred to as symmetric aggregation and a case in which thenumber of downlink CCs and the number of uplink CCs are different fromeach other is referred to as asymmetric aggregation.

Meanwhile, the carrier aggregation (CA) technologies, as describedabove, may be generally separated into an inter-band CA technology andan intra-band CA technology. The inter-band CA is a method thataggregates and uses CCs that are present in different bands from eachother, and the intra-band CA is a method that aggregates and uses CCs inthe same frequency band. Further, CA technologies are more specificallysplit into intra-band contiguous CA, intra-band non-contiguous CA, andinter-band non-contiguous CA.

FIGS. 6a and 6b are concept views illustrating intra-band carrieraggregation (CA).

FIG. 6a illustrates intra-band contiguous CA, and FIG. 6b illustratesintra-band non-contiguous CA.

LTE-advanced adds various schemes including uplink MIMO and carrieraggregation in order to realize high-speed wireless transmission. The CAthat is being discussed in LTE-advanced may be split into the intra-bandcontiguous CA shown in FIG. 6a and the intra-band non-contiguous CAshown in FIG. 6 b.

FIGS. 7a and 7b are concept views illustrating inter-band carrieraggregation.

FIG. 7a illustrates a combination of a lower band and a higher band forinter-band CA, and FIG. 7b illustrates a combination of similarfrequency bands for inter-band CA.

In other words, the inter-band carrier aggregation may be separated intointer-band CA between carriers of a low band and a high band havingdifferent RF characteristics of inter-band CA as shown in FIG. 7a andinter-band CA of similar frequencies that may use a common RF terminalper component carrier due to similar RF (radio frequency)characteristics as shown in FIG. 7b .

TABLE 1 Uplink (UL) Downlink (DL) Operating operating band operatingband Duplex Band F_(UL) _(—) _(low)-F_(UL) _(—) _(high) F_(DL) _(—)_(low)-F_(DL) _(—) _(high) Mode 1 1920 MHz-1980 MHz  1920-1 MHz 1980 MHz2 1850 MHz-1910 MHz 1930 MHz-1990 MHz FDD 3 1710 MHz-1785 MHz 1805MHz-1880 MHz FDD 4 1710 MHz-1755 MHz 2110 MHz-2155 MHz FDD 5 824 MHz-849MHz 869 MHz-894 MHz FDD 61 830 MHz-840 MHz 875 MHz-885 MHz FDD 7 2500MHz-2570 MHz 2620 MHz-2690 MHz FDD 8 880 MHz-915 MHz 925 MHz-960 MHz FDD9 1749.9 MHz-1784.9 MHz 1844.9 MHz-1879.9 MHz FDD 10 1710 MHz-1770 MHz2110 MHz-2170 MHz FDD 11 1427.9 MHz-1447.9 MHz 1475.9 MHz-1495.9 MHz FDD12 699 MHz-716 MHz 729 MHz-746 MHz FDD 13 777 MHz-787 MHz 746 MHz-756MHz FDD 14 788 MHz-798 MHz 758 MHz-768 MHz FDD 15 Reserved Reserved FDD16 Reserved Reserved FDD 17 704 MHz-716 MHz 734 MHz-746 MHz FDD 18 815MHz-830 MHz 860 MHz-875 MHz FDD 19 830 MHz-845 MHz 875 MHz-890 MHz FDD20 832 MHz-862 MHz 791 MHz-821 MHz FDD 21 1447.9 MHz-1462.9 MHz 1495.9MHz-1510.9 MHz FDD 22 3410 MHz-3490 MHz 3510 MHz-3590 MHz FDD 23 2000MHz-2020 MHz 2180 MHz-2200 MHz FDD 24 1626.5 MHz-1660.5 MHz 1525MHz-1559 MHz FDD 25 1850 MHz-1915 MHz 1930 MHz-1995 MHz FDD 26 814MHz-849 MHz 859 MHz-894 MHz FDD 27 807 MHz-824 MHz 852 MHz-869 MHz FDD28 703 MHz-748 MHz 758 MHz-803 MHz FDD 29 N/A N/A 717 MHz-728 MHz FDD 302305 MHz-2315 MHz 2350 MHz-2360 MHz FDD 31 452.5 MHz-457.5 MHz 462.5MHz-467.5 MHz FDD 32 N/A N/A 1452 MHz-1496 MHz FDD . . . 33 1900MHz-1920 MHz 1900 MHz-1920 MHz TDD 34 2010 MHz-2025 MHz 2010 MHz-2025MHz TDD 35 1850 MHz-1910 MHz 1850 MHz-1910 MHz TDD 36 1930 MHz-1990 MHz1930 MHz-1990 MHz TDD 37 1910 MHz-1930 MHz 1910 MHz-1930 MHz TDD 38 2570MHz-2620 MHz 2570 MHz-2620 MHz TDD 39 1880 MHz-1920 MHz 1880 MHz-1920MHz TDD 40 2300 MHz-2400 MHz 2300 MHz-2400 MHz TDD 41 2496 MHz 2690 MHz2496 MHz 2690 MHz TDD 42 3400 MHz-3600 MHz 3400 MHz-3600 MHz TDD 43 3600MHz-3800 MHz 3600 MHz-3800 MHz TDD 44 703 MHz-803 MHz 703 MHz-803 MHzTDD

The 3GPP LTE/LTE-A system defines uplink and downlink operating bands asin Table 1. The four CA cases illustrated in FIGS. 6 and 7 are dividedaccording to Table 1.

Here, F_(UL_low) denotes the lowest frequency in an uplink operatingband. F_(UL_high) denotes the highest frequency in an uplink operatingband. F_(DL_low) denotes the lowest frequency in a downlink operatingband. F_(DL_high) denotes the highest frequency in a downlink operatingband.

When operating bands are set as in Table 1, the frequency distributionorganization of each country may allocate a particular frequency to aservice provider according to the situation of each country.

As described above, the 3GPP LTE system supports channel bandwidths of1.4 MHz, 3 MHz, 5 MHz, 10 MHz, 15 MHz, and 20 MHz. The relationshipbetween a channel bandwidth and the number of resource blocks is asfollows.

TABLE 2 BW_(Channel) [MHz] 1.4 3 5 10 15 20 Transmission 6 15 25 50 75100 bandwidth configuration N_(RB)

Wireless transmission causes unwanted emission to adjacent bands. Here,regarding interference by emission due to transmission by a BS, thelevel of interference introduced into adjacent bands may be reduced tobe an allowable threshold or lower using the characteristics of the BS,such as by designing an expensive and large-sized RF filter. Regardinginterference by a UE, however, it is difficult to completely prevent theintroduction of interference into adjacent bands due to limits on UEsize or the price of a power amplifier or a pre-duplex filter RF device.

Therefore, it is necessary to limit the transmission power of a UE.

Maximum power (Pcmax) actually available for a UE in the LTE system issimply represented as follows.Pc max=Min(Pe max,Pu max)  [Equation 1]

Here, Pcmax denotes the maximum transmission power available for a UE(actual maximum transmission power) on a cell, and Pemax denotes themaximum allowed power on the cell that is signalled by a BS. Further,Pumax denotes the maximum power (P_(PowerClass)) for the UE adjustedaccording to the maximum power reduction (hereinafter, MPR), theadditional MPR (hereinafter, A-MPR), or the like.

The maximum power (P_(PowerClass)) for the UE is illustrated as below.

TABLE 3 Operating Power class 1 Power class 3 band (dBm) (dBm) 1, 2, 3,4, 5, 6, 7, 8, 9, 10, 11, 12, 23 dBm 13, 14, 17, 18, 18, 19, 20, 21, 22,23, 24, 25, 26, 27, 28, 30, 31, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42,43, 44 14 31 dBm

In intra-band contiguous CA, the maximum power (P_(PowerClass)) for theUE is illustrated as below.

TABLE 4 Operating Power class 3 band (dBm) CA_1C  23 dBm CA_3C  23 dBmCA_7C  23 dBm CA_38C 23 dBm CA_39C 23 dBm CA_40C 23 dBm CA_41C 23 dBmCA_42C 23 dBm

FIG. 8 illustrates a method for limiting the transmission power of a UE.

As illustrated in (a) of FIG. 8, a UE performs transmission with limitedtransmission power.

When a peak-to-average power ratio (PAPR) is high, the linearity of apower amplifier (PA) decreases accordingly. Thus, to maintain thelinearity, an MPR value of up to 2 dB for limiting transmission powermay be applied depending on the modulation scheme.

(A) MPR in 3GPP Release 11

According to 3GPP Release 11, a UE may adopt multi-clusteredtransmission for a single component carrier (CC) and thus maysimultaneously transmit a PUSCH and a PUCCH. When the PUSCH and thePUCCH are simultaneously transmitted, the size of IM3 components(distorted signals generated by intermodulation) occurring in anout-of-band region may increase, and accordingly the IM3 components mayact as greater interference in an adjacent band. Therefore, an MPR valuemay be set to satisfy UE's emission requirements the UE needs to followfor uplink transmission, such as general spurious emission (SE), anadjacent channel leakage ratio, and a general spectrum emission mask(SEM).

(B) A-MPR

As illustrated in (b) of FIG. 8, a BS may transmit a network signal (NS)to a UE 100, thereby applying A-MPR. Unlike in MPR mentioned above, inA-MPR, in order not to cause an impact on, for example, interference in,an adjacent band, a BS transmits a network signal (NS) to a UE 100operating in a particular operating band so that the UE 100 additionallyreduces power. That is, when an MPR-applied UE receives a network signal(NS), the UE additionally applies an A-MPR to determine transmissionpower.

The following table illustrates an A-MPR value according to the networksignal.

TABLE 5 Network Channel Number of signaling E-UTRA bandwidth resourceblocks A-MPR value band (MHz) (N_(RB)) (dB) NS_01 Entire LTE 1.4, 3, 5,N/A operating 10, 15, 20 band NS_03 2, 4, 10, 23,  3 >5 ≤1 25, 35, 36, 5 >6 ≤1 66 10 >6 ≤1 15 >8 ≤1 20 >10 ≤1 NS_04 41 5, 10, 15, 20 See Table6 NS_05  1 10, 15, 20 ≥50 ≤1 15, 20 See Table 7 65 10, 15, 20 ≥50 ≤1 15,20 See Table 7 NS_06 12, 13, 14, 17 1.4, 3, 5, 10 N/A NS_07 13 10 SeeTable 8 NS_08 19 10, 15 >44 ≤3 NS_09 21 10, 15 >40 ≤1 >55 ≤2 . . . NS_18 5 ≥2 ≤1 10, 15, 20 ≥1 ≤4 . . . NS_24 65 5, 10, 15, 20 See Table 9 NS_2565 5, 10, 15, 20 See Table 10 NS_26 68  5, 10, 15 See Table 11

The following table illustrates an A-MPR requirement according to“NS_04” signaling with bandwidth >5 MHz.

TABLE 6 Channel bandwidth [MHz] Parameter 5 Fc [MHz] ≤2499.5 >2499.5RB_(start) 0-8 9-24 0-24 L_(CRB) [RBs] >0 >0 >0 A-MPR ≤2 0 0 [dB] 10 Fc[MHz] ≤2504 >2504 RB_(start) 0-8   9-35 36-49 0-49 L_(CRB) [RBs] ≤15 >15and <25 ≥25 N/A >0 >0 RB_(start) + N/A N/A N/A ≥45 N/A N/A L_(CRB) [RBs]A-MPR ≤3 ≤1 ≤2 ≤1 0 0 [dB] 15 Fc [MHz] ≤2510.8 >2510.8 RB_(start) 0-1314-59 60-74 0-74 L_(CRB) [RBs] ≤18 or ≥36 >18 and <36 N/A >0 >0RB_(start) + N/A N/A ≥62 N/A N/A L_(CRB) [RBs] A-MPR ≤3 ≤1 ≤1 0 0 [dB]20 Fc [MHz] ≤2517.5 >2517.5 RB_(start) 0-22 23-76 77-99 0-99 L_(CRB)[RBs] ≤18 or ≥40 >18 and <40 N/A >0 >0 RB_(start) + N/A N/A ≥86 N/A N/AL_(CRB) [RBs] A-MPR ≤3 ≤1 ≤1 0 0 [dB]

The following table illustrates an A-MPR according to “NS_05” signaling.

TABLE 7 Channel bandwidth [MHz] Parameter 15 Fc [MHz] 1932.5 RB_(start)0-7 8-66 67-74 L_(CRB) [RBs] ≥1 ≤30 31-54 >54 ≤6 >6 A-MPR [dB] ≤11 0 ≤3≤5 ≤5 ≤1 20 Fc [MHz] 1930 RB_(start) 0-23 24-75 76-99 L_(CRB) [RBs] ≥1≤24 25-40 41-50 >50 ≤6 >6 A-MPR [dB] ≤11 0 ≤3 ≤5 ≤10 ≤5 ≤1

The following table illustrates an A-MPR according to “NS_07” signaling.

TABLE 8 Parameter Region A Region B Region C RB_(start) 0-12 13-18 19-4243-49 L_(CRB) [RBs] 6-8 1 to 5 and  ≥8 ≥18 ≤2 9-50 A-MPR [dB] ≤8 ≤12 ≤12 ≤6 ≤3

The following table illustrates an A-MPR according to “NS_24” signaling.

TABLE 9 Channel bandwidth [MHz] Parameter 5 Fc [MHz] Fc > [1987.5]RB_(start) 0-24 L_(CRB) [RBs] 0-24 A-MPR [dB] ≤10 10 Fc [MHz] 1975 < Fc≤ 1985 1985 < Fc ≤ 1995 Fc > 1995 RB_(start) 0-1 2-14 15-26 36-49 0-490-49 L_(CRB) [RBs] >10 ≥35 N/A ≤2 >11 0-49 0-49 RB_(end) N/A N/A >48 N/AN/A N/A N/A A-MPR [dB] ≤2 ≤2 1 ≤3 ≤1 ≤9 ≤17 15 Fc [MHz] 1972.5 < Fc ≤1987.5 Fc > 1987.5 RB_(start) 0-11 12-74 0-74 L_(CRB) [RBs] ≤45 >45 >30-74 RB_(end) N/A N/A ≥45 N/A A-MPR [dB] ≤2 ≤8 ≤7 ≤17 20 Fc [MHz] Fc >1970 RB_(start) 0-99 L_(CRB) [RBs] 0-99 A-MPR [dB] ≤17

The following table illustrates an A-MPR according to “NS_25” signaling.

TABLE 10 Channel bandwidth [MHz] Parameter 5 Fc [MHz] Fc > [1997.5]RB_(start) 0-9 10-24 L_(CRB) [RBs] >12 N/A RB_(end) N/A ≥22 A-MPR [dB]≤5 ≤2 10 Fc [MHz] 1975 < Fc ≤ 1985 < Fc ≤ 1995 Fc > 1995 1985 RB_(start)0-1 2-49 0 1-18 19-49 0-6 7-15 16-49 L_(CRB) [RBs] >10 N/A ≤25 >25 >25N/A N/A >20 N/A RB_(end) N/A >48 N/A N/A N/A >42 N/A N/A >35 A-MPR [dB]≤1 ≤1 ≤1 ≤5 ≤5 ≤1 ≤10 <7 ≤11 15 Fc [MHz] 1972.5 < Fc ≤ 1987.5 Fc >1987.5 RB_(start) 0-4 5-30 31-62 63-74 0-74 L_(CRB) [RBs] ≥15 ≥45 N/AN/A 0-74 RB_(end) N/A N/A >71 N/A N/A A-MPR [dB] ≤4 ≤3 ≤1 ≤1 ≤13 20 Fc[MHz] 1970 < Fc ≤ 1990 Fc > 1990 RB_(start) 0-13 14-40 41-99 0-99L_(CRB) [RBs] N/A ≥32 N/A 0-99 RB_(end) N/A N/A >72 N/A A-MPR [dB] ≤11≤11 ≤13 ≤13

The following table illustrates an A-MPR according to “NS_26” signaling.

TABLE 11 Bandwidth (MHz) RBstart L_crb A-MPR 5 0 ≤1 ≤[0~1] 0-1  ≥24≤[0~1] 10 0-10 ≤1 ≤1 15 0-17 ≥1 ≤1

The transmission power of a UE may be represented by the followingequation for obtaining P_(cmax).

P_(cmax) needs to satisfy the following condition.P _(CMAX_L) ≤P _(CMAX) ≤P _(CMAX_H)  [Equation 2]

P_(CMAX_L) is a lower bound, which is obtained as follows.P _(CMAX_L)=MIN {P _(EMAX) −ΔT _(C) ,P_(PowerClass)−MAX(MPR+A-MPR,P-MPR)−ΔT _(C)}  [Equation 3]

P_(CMAX_H) is an upper bound, which is obtained as follows.P _(CMAX_H)=MIN {P _(EMAX) ,P _(PowerClass)}  [Equation 4]

P_(EMAX) is given P-Max through an RRC signal. P_(PowerClass) denotesthe maximum UE power considering an allowable value. P-MPR denotes anallowable maximum transmission power reduction. P-MPR may be obtainedusing an equation for obtaining P_(CMAX). ΔT_(C) may be 0 dB or 1.5 dB.

(C) A-MPR in CA

Considering CA, an uplink channel bandwidth may be increased to up to 40MHz (20 MHz+20 MHz), and thus a greater MPR value is needed. Thus, whena BS transmits a network signal to a UE in order to protect a particularband in the CA environment, additional power reduction may be performedfor a UE operating in the particular band, thereby protecting adjacentbands.

<Introduction of Small Cell>

In a next-generation mobile communication system, it is expected that asmall cell with a small cell coverage radius is added in the coverage ofa legacy cell and that the small cell handles a greater amount oftraffic. The legacy cell has greater coverage than that of the smallcell and thus is also referred to as a macrocell. Hereinafter, it isdescribed with reference to FIG. 9.

FIG. 9 shows a heterogeneous network environment, in which a macrocelland a small cell coexist, as a potential next-generation wirelesscommunication system.

FIG. 9 shows a heterogeneous network environment in which a macrocell bya legacy BS 200 overlaps with one or more small cells by small BSs 300a, 300 b, 300 c, and 300 d. The legacy BS provides greater coverage thanthose of the small BSs and thus is also referred to as a macro BS (macroeNodeB or MeNB). In the present specification, the terms “macrocell” and“macro BS” may be used together. A UE connected to the macrocell 200 maybe referred to as a macro UE. The macro UE receives a downlink signalfrom the macro BS and transmits an uplink signal to the macro BS.

In such a heterogeneous network, coverage holes of the macrocell can befilled by configuring the macrocell as a primary cell (Pcell) and byconfiguring the small cells as a secondary cell (Scell). In addition,overall performance can be boosted by configuring the small cells as aPcell and by configuring the macrocell as a Scell.

<Device-to-Device (D2D) Communication>

Hereinafter, D2D communication that is expected to be introduced in anext-generation communication system is described.

FIG. 10a illustrates the concept of D2D communication that is expectedto be introduced in a next-generation communication system.

With increasing demands for social networking services (SNSs) fromusers, communication between user equipments (UEs) physically adjacent,that is, D2D communication, is required.

To reflect the foregoing requirements, discussions have been conductedon methods for enabling direct communication between UE #1 100-1, UE #2100-2 and UE #3 100-3 or between UE #4 100-4, UE #5 100-5 and UE #6100-6 without BS (eNodeB) intervention, illustrated in FIG. 10a . Directcommunications between UE #1 100-1 and UE #4 100-4 is also possible withthe aid of the BS (eNode) 200. UE #1 100-1 may also serve as a relay forUE #2 100-2 and UE #3 100-3. Likewise, UE #4 100-4 may serve as a relayfor UE #5 100-5 and UE #6 100-6, which are distant from the center ofthe cell.

A link between UEs used for D2D communication is also referred to as asidelink. Further, D2D is also referred to as proximity service (ProSe)communication.

Physical channels used for a sidelink are listed as follows.

-   -   Physical Sidelink Shared Channel (PSSCH)    -   Physical Sidelink Control Channel (PSCCH)    -   Physical Sidelink Discovery Channel (PSDCH)    -   Physical Sidelink Broadcast Channel (PSBCH)

As described above, it is expected that D2D communication between UEs isintroduced in an upcoming system.

FIG. 10b illustrates an example of transmitting a discovery signal forD2D communication.

UE #1 100-1 illustrated FIG. 10b may transmit a discovery signal inorder to detect whether there is a suitable neighboring UE for D2Dcommunication or to report the presence of UE #1 100-1.

Resources for sidelink communication may be allocated according to thefollowing two modes.

In a first mode (or mode I), resources for sidelink communication areallocated by a serving cell. To this end, a UE needs to be in anRRC-connected state. The UE requests resource allocation from theserving cell, and the serving cell allocates resources for thetransmission of sidelink control information and data.

In a second mode (or mode II), a UE autonomously selects a resource. TheUE autonomously selects resources for sidelink communication from aresource pool.

<Disclosure of the Present Specification>

As described above, when one UE simultaneously performs cellulartransmission (wide area network (WAN) transmission) and D2Dtransmission, in configuring transmission power for the UE, a higherpriority is basically set for protecting legacy cellular data. In thiscase, power for cellular transmission needs to be maintained, and D2Dtransmission power needs to be adjusted so that the total transmissionpower does not exceed the maximum power for the UE. Therefore, thepresent specification proposes a method for adjusting only D2Dtransmission power so that total transmission power does not exceedmaximum transmission power when cellular transmission and D2Dtransmission overlap over a certain interval,

FIG. 11a illustrates an example in which a band used for D2Dcommunication is different from an LTE/LTE-A band used for cellularcommunication, and FIG. 11b illustrates an RF structure.

When an operating band for D2D communication and an operating band forcellular communication are different as illustrated in FIG. 11a , thestructure illustrated in FIG. 11b is proposed, which uses a radiofrequency integrated circuit (RFIC, including an amplifier, a synthesisunit, a filter, and a baseband unit) that accommodates an RF chainallocated for each band, similar to an LIE-A Release 10 structure.

FIG. 11b shows the RFIC 130-21 that accommodates a plurality of RFchains, a plurality of duplexers, a first band (e.g., high band) switch130-28 a to divide a plurality of high bands, a second band (e.g., lowband) switch 130-28 b to divide a plurality of low bands, and a diplexer130-29.

A first duplexer 130-27 a among the plurality of duplexers separates atransmission signal from a reception signal in a band X for cellularcommunication. A first PA 130-22 a and a first LNA 130-23 a areconnected to the first duplexer 130-27 a and the RFIC 130-21.

When only the band X is used for cellular communication and a band Y isdeactivated. When the band Y is used for D2D communication, a secondduplexer 130-27 b among the plurality of duplexers separates a D2Dtransmission signal from a D2D reception signal in the band Y for D2Dcommunication. A second PA 130-22 b, a second LNA 130-23 b, adirectional coupler 130-24, a switch 130-25, and a third LNA 130-23 care connected to the second duplexer 130-27 b and the RFIC 130-21.

A third duplexer among the plurality of duplexers separates atransmission signal from a reception signal in a band Z.

The diplexer 130-29 synthesizes/separates low-band and high-bandtransmission/reception signals and is connected to the first band (e.g.,high band) switch 130-28 a and the second band (e.g., low hand) switch130-28 h.

The first band switch 130-28 a selectively exchanges a signal with anyone of the first duplexer 130-27 a for the band X for cellularcommunication, the second duplexer 130-27 b for the band Y for D2Dcommunication, and the third duplexer for the hand Z. Likewise, thesecond band switch 130-28 b selectively exchanges a signal with any oneof a fourth duplexer, a fifth duplexer, and a sixth duplexer.

The first duplexer 130-27 a separates a transmission signal and areception signal of cellular communication and transmits the separatedsignals between the first hand switch 130-28 a and the RFIC 130-21. Thefirst PA 130-22 a is connected to a transmission line between the bandduplexer 130-27 a and the RFIC 130-21, and the first LNA 130-23 a isconnected to a reception line therebetween.

The second duplexer 130-27 b separates a transmission signal and areception signal of D2D communication and transmits the separatedsignals between the first band switch 130-28 a and the RFIC 130-21. Thefirst PA 130-22 a and the directional coupler 130-24 are connected to atransmission line between the second duplexer 130-27 b d the RFIC130-21, and the second LNA 130-23 b is connected to a reception linetherebetween. The switch 130-25 and the third LNA 130-23 c are connectedto the directional coupler 130-24.

The operation of the RF structure illustrated in FIG. 11b is dividedinto transmission and reception as described below.

First, a reception operation will be described as follows.

When a signal is received through an antenna, the diplexer 130-29transmits the signal to either the first band switch 130-28 a or thesecond band switch 130-28 b. When the first band switch 130-28 areceives the received signal from the diplexer 130-29, the first bandswitch 130-28 a transmits the signal to one or more of the firstduplexer 130-27 a and the second duplexer 130-27 b. When the receivedsignal is a received signal of cellular communication, the firstduplexer 130-27 a transmits the received signal of cellularcommunication to the RFIC 130-21 via the first LNA 130-23 a. When thereceived signal is a received signal of D2D communication in the band Y,the second duplexer 130-27 b transmits the received signal of D2Dcommunication to the directional coupler 130-24, the directional coupler130-24 transmits the received signal of D2D communication to the thirdLNA 130-23 c, and then the received signal of D2D communication istransmitted to the RFIC 130-21 via the third LNA 130-23 c. When acellular signal in the band Y is received, the signal passes through thesecond duplexer 130-27 b and is then transmitted to the RFIC 130-21 viathe second LNA 130-23 b.

Next, a transmission operation will be described as follows.

A transmission signal of cellular communication in the band X outputfrom the RFIC 130-21 is amplified through the first PA 130-22 a and istransmitted to the first duplexer 130-27 a. The first duplexer 130-27 atransmits the amplified transmission signal of cellular communication tothe first band switch 130-28 a. A transmission signal of D2Dcommunication in the band Y output from the RFIC 130-21 is amplifiedthrough the second PA 130-22 b and is transmitted to the directionalcoupler 130-24, and the directional coupler 130-24 transmits theamplified transmission signal of D2D communication to the secondduplexer 130-27 b. The second duplexer 130-27 b transmits the amplifiedtransmission signal of D2D communication to the first hand switch 130-28a. The first band switch 130-28 a selectively transmits the amplifiedtransmission signal of cellular communication and the amplifiedtransmission signal of D2D communication or transmits all of the twotransmission signals to the diplexer 130-29 through a diplexer addedbetween the first band switch and the duplexer.

Based on the above RF structure, the present specification proposes amethod in which a UE performing D2D communication (hereinafter, referredto as a D2D UE or a ProSe UE) efficiently determines transmission powerfix a D2D signal.

Carriers for D2D communication and carriers for cellular communicationmay be aggregated as the following combinations.

-   -   USA: B2(D2D)+B4(WAN)    -   Region 1 and Region 3: B28(D2D)+B1(WAN)

FIGS. 12a to 12c illustrate bands for D2D transmission/reception and forWAN transmission/reception.

As illustrated in FIG. 12a , band 1 is a band in which a UE receives asignal from a serving cell of a BS, while band 28 is an unassigned bandin which no WAN service is performed, which is not for receiving datafrom the serving cell of the cellular BS. Here, D2Dtransmission/reception may be performed on an uplink of band 28 wherethe serving cell does not operate.

As illustrated in FIG. 12b , band 28 may be a band in which a Pcell of acellular BS operates, and band 1 may be a band in which a Scell of thecellular BS operates. Here, D2D transmission/reception may be performedon an uplink of band 28 in which the Pcell of the BS operates. However,since a D2D operation in Release 13 currently supports only asimultaneous transmission/reception operation in an inter-band, a D2Doperation and a WAN operation in the Pcell is excluded.

As illustrated in FIG. 12c , band 28 may be a band in which a Scell of acellular BS operates, and band 1 may be a band in which a Pcell of thecellular BS operates. Here, D2D transmission/reception may be performedon an uplink of band 28 in which the Scell of the BS operates.

Here, when a D2D signal is currently transmitted through the Scell, thatis, a secondary component carrier (SCC), transmission power for a D2D UEis configured as follows.

Here, only Pmpr,c=0 dB is considered. When Pmpr,c≠0, the value ofP_(Powerclass) minus Pmpr,c is the maximum transmission power of the UE.

A. Transmission power configured for D2D UE (or ProSe UE)

Requirements for the configured maximum output power P_(CMAX,c) and apower boundary are defined as follows.

-   -   MPR_(c)    -   A-MPR_(c)    -   ΔT_(ProSe)=0.1 dB

For P_(CMAX,PSSCH) and P_(CMAX,PSCCH), P_(EMAX,c) is a value providedfrom serving cell C via P-Max. P_(EMAX,c) is a value provided from ahigher layer via max TXPower when a UE does not operate on a carrier forD2D communication or ProSe communication.

For P_(CMAX,PSDCH), P_(EMAX,c) is a value provided from a higher layervia a discMaxTxPower parameter.

For P_(CMAX,PSBCH), P_(EMAX,c) is a value provided from a higher layervia maxTxPower when a UE does not operate on a carrier for D2Dcommunication or ProSe communication. When the UE does not operate inthe serving cell, if PSBCH/SLSS transmission is triggered for directProSe communication, P_(EMAX,c) is a value provided from a higher layervia P-Max or a value provided from a higher layer via discMaxTxPower.

P_(CMAX,SSSS) is a value using P_(CMAX,PSBCH), to which an MPR isapplied, for SSSS transmission, in order to reduce a PAPR and a cubicmetric.

Transmission power configured for WAN communication and D2Dcommunication in different bands (that is, inter-band) may be determinedbetween P_(CMAX_L) and P_(CMAX_H) of each serving cell used for twouplink transmission through conventional inter-band CA. On the otherhand, when obtained P_(CMAX_L) is 23 dBm, which is equivalent to powerclass 3, and P_WAN+P_D2D23 dBm in one subframe where WAN transmissionand D2D transmission are simultaneously performed, where P_WAN<23 dB,P_WAN is set to configured transmission power and P_D2D is determined tobe [P_(powerclass)−P_WAN](obtained via conversion on a linear scale,equation application, and conversion on a logarithmic scale) or lower.That is, transmission power on each carrier in WAN transmission and WANtransmission is configured to decrease at the same rate in order to meetP_(Powerclass) and is configured such that total power does not exceedthe power class. However, since the priority of a WAN needs to be alwaysguaranteed in WAN transmission and D2D transmission, transmission powerfor cellular communication maintains the same value without beingaffected by D2D transmission, whereas D2D transmission power is reducedor D2D transmission may not be performed so that the total power doesnot exceed the power class, which is described in the following example.

When P_WAN is 21 dBm, P_D2D for a UE of power class 3 needs to be 18.67dBm or lower so that the total power does not exceed 23 dBm. Further,when WAN communication and D2D communication are performedasynchronously, if WAN transmission time is earlier than D2D (that is,WAN transmission leads) or if D2D transmission time is earlier than WANtransmission time (that is, D2D transmission leads), P_(CMAX) needs tobe determined based on a subframe n for WAN transmission.

The foregoing details may be properly summarized as follows.

B. Improvement in transmission power configured for D2D UE (or ProSe UE)

Requirements for the configured maximum output power P_(CMAX,c) and apower boundary are defined as follows.

-   -   MPR_(c)    -   A-MPR_(c)    -   ΔT_(ProSe)=0.1 dB

Regarding P_(CMAX,PSSCH) and P_(CMAX,PSCCH), P_(EMAX,c) is a valueprovided from serving cell C via P-Max. P_(EMAX,c) is a value providedfrom a higher layer via maxTXPower when a UE does not operate on acarrier for D2D communication or ProSe communication.

Regarding P_(CMAX,PSDCH), P_(EMAX,c) is a value provided from a higherlayer via a discMaxTxPower parameter.

Regarding P_(CMAX,PSBCH), P_(EMAX,c) is a value provided from a higherlayer via maxTxPower when a UE does not operate on a carrier for D2Dcommunication or ProSe communication. When the UE does not operate inthe serving cell, if PSBCH/SLSS transmission is triggered for directProSe communication, P_(EMAX,c) is a value provided from a higher layervia P-Max or a value provided from a higher layer via discMaxTxPower.

P_(CMAX,SSSS) is a value using P_(CMAX,PSBCH,) to which an MPR isapplied for SSSS transmission.

Simultaneous WAN transmission and D2D transmission using one servingcell and inter-band aggregation may be represented as follows.P _(CMAX_L)=MIN {10 log₁₀Σ MIN [p _(EMAX,c)/(Δt _(C,c)),p_(PowerClass/)(mpr_(c) ·a-mpr_(c) ·Δt _(C,c) ·Δt _(IB,c) ·ΔT_(ProSe,c)),p _(PowerClass)/pmpr_(c],) P _(PowerClass)}  [Equation 5]P _(CMAX_H)=MIN {10 log₁₀ Σp _(EMAX,c) ,P _(PowerClass)}  [Equation 6]

When WAN transmission and D2D transmission are synchronously performedusing inter-band aggregation, P_(CMAX,C) for WAN transmission isdetermined and P_(CMAX,C) for D2D transmission is applied.

When WAN transmission and D2D transmission are asynchronously performedusing inter-band aggregation, if WAN transmission is performed in asubframe n and D2D transmission is performed in a subframe m, areference subframe for determining transmission power is always thesubframe n for WAN transmission.

Here, when D2D transmission starts ahead of WAN transmission (that is,D2D transmission leads), a pair of (n, m) and (n, m+1) needs to beconsidered to determine P_(CMAX), that is, to obtain P_(CMAX_L) andP_(CMAX_H).

However, when WAN transmission starts ahead of D2D transmission (thatis, WAN transmission leads), a pair of (n, m) and (n, m−1) needs to beconsidered to determine P_(CMAX), that is, to obtain P_(CMAX_L) andP_(CMAX_H).

Here, P_(CMAX_L) and P_(CMAX_H) are defined as follows.

When D2D transmission starts ahead of WAN transmission (that is, D2Dtransmission leads), P_(CMAX_L) and P_(CMAX_H) are defined as follows.P _(CMAX_L)=MIN {P _(CMAX_L)(n,m),P _(CMAX_L)(n,m+1)}P _(CMAX_H)=MAX {P _(CMAX_H)(n,m),P _(CMAX_H)(n,m+1)}  [Equation 7]

However, when WAN transmission starts ahead of D2D transmission (thatis, WAN transmission leads), P_(CMAX_L) and P_(CMAX_H) are defined asfollows.P _(CMAX_L)=MIN {P _(CMAX_L)(n,m−1),P _(CMAX_L)(n,m)}P _(CMAX_H)=MAX {P _(CMAX_H)(n,m−1),P _(CMAX_H)(n,m)}  [Equation 8]

When P_(CMAX,L)=P_(PowerClass) and P_(CMAX,C) for WANtransmission<P_(PowerClass), transmission power configured for WANtransmission needs to meet (satisfy) obtained P_(CMAX,L). Transmissionpower configured for D2D transmission needs to be adjusted not to exceedP_(PowerClass) of a UE in any time interval.

This can be explained considering the following two cases. A first caseis where WAN transmission and D2D transmission correspond to inter-bandCA and time synchronization between WAN transmission and D2Dtransmission is achieved to a certain extent (up to 32.47 us). A secondcase is where WAN transmission and D2D transmission are directed togeographically different destinations (inter-site) and timesynchronization therebetween is not achieved. The two cases are referredto as case 1 and case 2 as follows.

Case 1. Time Synchronization Between WAN Transmission and D2DTransmission is Achieved to a Certain Extent

FIG. 13 illustrates that time synchronization between WAN transmissionand D2D transmission is achieved to a certain extent.

In an environment where time synchronization between inter-bands isachieved, D2D transmission using a lower band (e.g., band 28) has widercoverage than WAN transmission using a higher band (e.g., band 1) andthus has a greater timing advance (TA). Therefore, when the timesynchronization operates within 32.47 us, WAN transmission time and D2Dtransmission time are as illustrated in FIG. 13.

FIG. 14a illustrates subframes for WAN transmission and D2D transmissionthrough a resource based on a mode other than sidelink mode I (when D2Dcommunication is performed using control data from a BS) in thesynchronous environment of FIG. 13, and FIG. 14b illustrates subframesfor WAN transmission and D2D transmission through a resource based onmode I in the synchronous environment of FIG. 13.

As illustrated in FIG. 14a , when D2D transmission is performed througha resource based on a mode other than mode I (for example, mode II: D2DUE's autonomous RB assignment), D2D transmission time for a UE isdetermined based on WAN reception time.

A hatched portion in FIG. 14a indicates a period in which D2Dtransmission (D2D transmission through a resource based on a mode otherthan mode I) is not performed when the UE performs WAN transmission inCC1. A non-hatched portion indicates a subframe period in which WANtransmission and D2D transmission are simultaneously performed.

On the other hand, as illustrated in FIG. 14b , when D2D transmission isperformed through a resource based on mode I, D2D transmission time forthe UE is determined based on WAN transmission time for the UE.Therefore, as illustrated in FIG. 14b , D2D transmission may beperformed before WAN transmission. Here, the hatched portion indicates aperiod in which only D2D transmission is performed.

Referring to FIGS. 14a and 14b , even though time synchronizationbetween WAN transmission and D2D transmission is achieved to a certainextent, there may be a period in which only WAN transmission isperformed because WAN transmission starts ahead of D2D transmission andthere may be a period in which D2D transmission is performed alonebecause D2D transmission starts ahead of WAN transmission.

Accordingly, when time synchronization between WAN transmission and D2Dtransmission is achieved to a certain extent, transmission power for theUE may be determined as follows.P _(CMAX_L)=MIN {10 log₁₀Σ MIN [p _(EMAX,c)/(Δt _(C,c)),p_(PowerClass)/mpr_(c) ·a-mpr_(c) ·Δt _(C,c) ·Δt _(IB,c) ·ΔT_(ProSe,c)),p _(PowerClass)/pmpr_(c)],P _(PowerClass)}  [Equation 9]

Using the above equation, P_(CMAX_L) for each subframe is determined,which is the minimum value of total P_(CMAX,L) for individual slots,which is illustrated with reference to a drawing.

FIG. 15 illustrates WAN transmission power per slot for a UE in CC1 andD2D transmission power per slot for the UE in CC2.

As illustrated in FIG. 15, when P_(CMAX_L) for WAN transmissioncalculated for slot 1 is 22 dBm, P_(CMAX_L) for D2D transmissioncalculated for slot 1 is 20 dBm, P_(CMAX_L) for WAN transmissioncalculated for slot 2 is 21 dBm, and P_(CMAX_L) for D2D transmissioncalculated for slot 2 is 21 dBm, P_(CMAX,L)=23 dBm for slot 1 andP_(CMAX,L)=23 dBm for slot 2, and accordingly P_(CMAX,L)=23 dBm isfinally applied for a subframe.

Here, when WAN transmission and D2D transmission are simultaneouslyperformed, WAN transmission power is maintained to be a total of 21 dBm,and D2D transmission power is adjusted to 18.67 dBm or lower so that thetotal power does not exceed P_(Powerclass) of 23 dBm.

Case 1-1. D2D Transmission Time of UE=Reception Time of UE in theSynchronous Environment (Mode Other than Mode I)

As illustrated in FIG. 14a , when WAN transmission and D2D transmissiondo not overlap by about a TA period within a total subframe length of 1ms, configured transmission power is represented by P_(CMAX,L)=MIN{[10*log 10(10{circumflex over ( )}(A/10)+10{circumflex over( )}(A′/10))], P_(PowerClass)} for slot 1 and P_(CMAX,L)=MIN {[10*log 10(10{circumflex over ( )}(B/10)+10{circumflex over ( )}(B′/10))],P_(PowerClass)} for slot 2. A smaller value of these two values isP_(CMAX,L) for a corresponding subframe.

FIG. 16 illustrates WAN transmission power per slot for a UE in CC1 andD2D transmission power per slot for the UE in CC2 in the situation ofFIG. 14 a.

As illustrated in FIG. 16, when 10*log 10(10{circumflex over( )}(A/10)+10{circumflex over ( )}(A′/10)) is P_(Powerclass) of 23 dBmor higher in total transmission power for slot 1 and 10*log 10(10{circumflex over ( )}(B/10)+10{circumflex over ( )}(B′/10)) is lowerthan P_(Powerclass) (23 dBm) in total transmission power for slot 2,P_(CMAX,L) for a corresponding subframe is determined to be 10*log 10(10{circumflex over ( )}(B/10)+10{circumflex over ( )}(B′/10)). SinceP_(CMAX,L) applied to the entire subframe does not exceeds 23 dBm, WANtransmission power and D2D transmission power are the same as configuredfor each carrier (B dBm for WAN transmission and B′ dBm D2Dtransmission).

However, when P_(CMAX,L) per slot exceeds 23 dBm,P_(CMAX,L)=P_(PowerClass), which is set to 23 dBm as power class 3 for aUE. For example, when transmission power per slot is as illustrated inFIG. 15, WAN transmission power in CC1 may fixed to 21 dBm, and D2Dtransmission power in CC2 may be set to 18.67 dBm or lower, therebysatisfying the total power of 23 dBm.

Case 1-2. D2D Transmission Time=Transmission Time of UE in theSynchronous Environment (Mode I)

As illustrated in FIG. 14b , when D2D transmission is performed througha resource based on mode I, D2D transmission time for a UE is determinedbased on WAN transmission time for the UE, so that D21) transmission maystart before WAN transmission. In this case, transmission power isdescribed as below in FIG. 17.

FIG. 17 illustrates WAN transmission power per slot for a UE in CC1 andD2D transmission power per slot for the UE in CC2 in the situation ofFIG. 14 b.

As illustrated in FIG. 17, when WAN transmission and D2D transmission donot overlap by a certain time period within a subframe length of 1 ms,P_(CMAX,L)=MIN {[10*log 10(10{circumflex over ( )}(A/10)+10{circumflexover ( )}(A′/10))], P_(PowerClass)} for slot 1 and P_(CMAX,L)=MIN{[10*log 10 (10{circumflex over ( )}(B/10)+10{circumflex over( )}(B′/10))], P_(PowerClass)} for slot. A smaller value of these twovalues is P_(CMAX,L) for a corresponding subframe.

When transmission power for slot 1 exceeds P_(Powerclass) andtransmission power for slot 2 is lower than P_(Powerclass), P_(CMAX,L)to be applied to the subframe is set to a value lower than 23 dBm, andthus WAN transmission power and D2D transmission power are the same asconfigured values (B dBm for WAN transmission and B′ dBm D2Dtransmission).

However, when P_(CMAX,L) per slot exceeds 23 dBm,P_(CMAX,L)=P_(PowerClass). For example, when transmission power per slotis as illustrated in FIG. 15, WAN transmission power in CC1 may fixed to21 dBm, and D2D transmission power in CC2 may be set to 18.67 dBm orlower, thereby satisfying the total power of 23 dBm.

The details mentioned so far are summarized as follows.

In the case where D2D transmission time for a UE is determined based onWAN reception time for the UE or WAN transmission time for the UE in thesituation where time synchronization between WAN transmission and D2Dtransmission is achieved to a certain extent

(i) P_(CMAX,L)<23 dBm

-   -   WAN transmission power=calculated transmission power    -   D2D transmission power=calculated transmission power

(ii) P_(CMAX,L)=23 dBm

When WAN transmission power <23 dBm

-   -   WAN transmission power=calculated transmission power    -   D2D transmission power is adjusted not to exceed P_(Powerclass)

When WAN transmission power=23 dBm

-   -   No D2D transmission is performed

Case 2. Time Synchronization Between WAN Transmission and D2DTransmission is not Achieved

FIG. 18 illustrates that time synchronization between WAN transmissionand D2D transmission is not achieved.

FIG. 18 shows times for WAN communication and D2D communication in anasynchronous environment. Specifically, D2D transmission may start aheadof WAN transmission, or WAN transmission may start ahead of D2Dtransmission.

FIGS. 19a to 19d illustrate examples of WAN transmission time and D2Dtransmission time in the asynchronous environment of FIG. 18.

As illustrated in FIG. 19a , when D2D transmission is performed througha resource based on a mode (e.g., mode II) other than mode I, D2Dtransmission time for a UE may lead WAN transmission time for the UE inthe asynchronous environment. Therefore, a hatched portion in FIG. 19aindicates a period in which only D2D transmission is performed. A nonhatched portion indicates a subframe period in which WAN transmissionand D2D transmission are simultaneously performed.

Alternatively, as illustrated in FIG. 19b , when D2D transmission isperformed through a resource based on a mode (e.g., mode II) other thanmode I, WAN transmission time may lead D2D transmission time for the UEin the asynchronous environment. Here, a hatched portion indicates aperiod in which only WAN transmission is performed.

As illustrated in FIG. 19c , when D2D transmission is performed througha resource based on mode I, D2D transmission time for the UE may leadWAN transmission time for the UE in the asynchronous environment. Here,a hatched portion indicates a period in which only D2D transmission isperformed.

Alternatively, as illustrated in FIG. 19d , when the D2D transmission isperformed through a resource based on mode I, WAN transmission time maylead D2D transmission time in the asynchronous environment. Here, ahatched portion indicates a period in which only WAN transmission isperformed.

As illustrated in FIGS. 19a to 19d , in the environment where timesynchronization between WAN transmission and D2D transmission is notachieved, transmission power configured for a UE needs to be determinedbased on which transmission should be performed first.

A method for determining transmission power configured for a UE may beas follows.

Case 2-1. When D2D Transmission Time for a UE Leads WAN TransmissionTime for the UE in an Asynchronous Environment

In the asynchronous environment illustrated in FIG. 18, WAN transmissiontime and D2D transmission time may not coincide with each other by up to500 us (that is, the time length of one slot). This is similar to in adual-connectivity environment. Therefore, when the times do not coincideby up to one-slot time, P_(CMAX,L) cannot be compared between adjacentslots as in a synchronous system.

FIG. 20 illustrates transmission power per slot in the case where D2Dtransmission time leads WAN transmission time in the asynchronousenvironment of FIG. 18.

A hatched portion in FIG. 20 indicates a period in which only D2Dtransmission is performed. A non-hatched portion indicates a period inwhich WAN transmission and D2D transmission are simultaneouslyperformed. For a subframe in which WAN transmission and D2D transmissionare simultaneously performed, P_(CMAX_L) for each transmission obtained,among which a minimum value may be selected. Particularly, like in dualconnectivity, when WAN transmission and D2D transmission aresimultaneously performed in the asynchronous environment, both subframesm and m+1 for D2D transmission are affected by a subframe n for WANtransmission. Further, subframes n−1 and n for WAN transmission are notaffected by the subframe m for D2D transmission, and WAN transmissionpower on the subframes may be maintained as it is. That is, transmissionpower on a subframe for D2D transmission depends on WAN transmissionpower and is entirely influenced by P_(CMAX_L) obtained for a subframefor each WAN transmission.

Specifically, referring to FIG. 20, a UE first calculates P_(CMAX_L) forthe subframes m and m+1 where WAN transmission and D2D transmission aresimultaneously performed in order to obtain WAN transmission power forthe subframe n. That is, the UE calculates P_(CMAX_L) (n,m) for thesubframe n for WAN transmission and for the subframe m for D2Dtransmission. Further, the UE calculates P_(CMAX_L) (n,m+1) for thesubframe n for WAN transmission and for the subframe m+1 for D2Dtransmission and selects a minimum value from among the obtained valuesas P_(CMAX_L).

For example, when P_(CMAX_L) for WAN transmission has slot 1_1=20 dBmand slot 1_2=21 dBm and P_(CMAX_L) for D2D transmission has slot 1_1=19dBm, slot 1_2=19 dBm, slot 2_1=20 dBm, and slot 2_2=21 dBm,

P_(CMAX_L) (n, m)=22.54 dBm and P_(CMAX_L) (n, m+1)=23 dBm.

Since P_(CMAX_L)=MIN {P_(CMAX_L) (n,m), P_(CMAX_L) (n,m+1)} for thesubframe n for WAN transmission, the transmission power is finally setto 22.54 dBm. That is, the transmission power configured for thesubframe n for WAN transmission is 20 dBm, and transmission power forthe subframes m and m+1 for D2D transmission needs to be determine so asnot to affect the transmission power configured for WAN transmission.Accordingly, P_(CMAX_L) for the subframe m+1 is limited to up to 20 dBm(that is, adjusted such that the subframe m+1 for D2D transmission ≤20dBm).

P_(CMAX_L) for a subframe n+1 for next WAN transmission may be obtainedas follows. When P_(CMAX_L) for WAN transmission has slot 2_1=21 dBm andslot 2_2=22 dBm and P_(CMAX_L) for D2D transmission has slot 2_1=20 dBm,slot 2_2=20 dBm, slot 3_1=21 dBm, and slot 3_2=22 dBm, P_(CMAX_L) (n+1,m+1)=23 dBm and P_(CMAX_L) (n+1,m+2)=23 dBm. Since P_(CMAX_L)=MIN{P_(CMAX_L) (n+1,m+1), P_(CMAX_L) (n+1,m+2)} for the subframe n+1 forWAN transmission, the transmission power is finally set to 23 dBm. Inthis case, since WAN transmission power should also not be affected byD2D transmission, the transmission power for the subframe n+1 is set to21 dBm, and P_(CMAX_L) for D2D subframes m+1 and m+2 is limited to up to18.67 dBm (that is, adjusted such that D2D transmission subframem+1≤18.67 dBm and D2D transmission subframe m+2≤18.67 dBm).

As described above, only P_(CMAX_L) for a WAN transmission subframe isobtained and is applied to D2D transmission, thereby calculating totaltransmission power.

Case 2-2. When WAN Transmission Time for a UE Leads D2D TransmissionTime for the UE in an Asynchronous Environment

When WAN Tx leads D2D Tx in the asynchronous environment, P_(CMAX_L) maybe obtained using P_(CMAX_L)=MIN {P_(CMAX_L)(n,m−1), P_(CMAX_L) (n,m)}and transmission power for D2D subframes m−1 and m may be obtaineddepending on P_(CMAX_L). When there is no D2D signal in a subframe m−1,P_(CMAX_L)=P_(CMAX_L) (n,m).

FIG. 21 illustrates transmission power per slot in the case where WANtransmission time leads D2D transmission time in the asynchronousenvironment of FIG. 18.

A hatched portion in FIG. 21 indicates a period in which only WANtransmission is performed. A non-hatched portion indicates a period inwhich WAN transmission and D2D transmission are simultaneouslyperformed. For a subframe in which WAN transmission and D2D transmissionare simultaneously performed, P_(CMAX_L) for each transmission isobtained, among which a minimum value may be selected.

For example, when P_(CMAX_L) for WAN transmission has slot 1_1=20 dBmand slot 1_2=21 dBm and P_(CMAX_L) for D2D transmission has slot 1_1=20dBm, slot 1_2=20 dBm, slot 2_1=21 dBm, and slot 2_2=22 dBm, since no D2Dtransmission is performed via the subframe m−1, P_(CMAX_L) for asubframe n may be determined using only P_(CMAX_L) (n,m). This value is23 dBm, and accordingly transmission power configured for the subframe nfor WAN transmission is determined to be 20 dBm and transmission powerfor the subframe m for D2D transmission needs to be determined so as notto affect the configured transmission power. Thus, D2D transmissionpower P_(CMAX_L) for the subframe m is limited to up to 20 dBm.

P_(CMAX_L) for a subframe n+1 for next WAN transmission may be obtainedas follows. When P_(CMAX_L) for WAN transmission has slot 2_1=21 dBm andslot 2_2=22 dBm and P_(CMAX_L) for D2D transmission has slot 1_1=20 dBm,slot 1_2=20 dBm, slot 2_1=21 dBm, and slot 2_2=22 dBm, P_(CMAX_L)(n+1,m)=23 dBm and P_(CMAX_L) (n+1,m+1)=23 dBm. Therefore, sinceP_(CMAX_L)=MIN {P_(CMAX_L) (n+1,m), P_(CMAX_L) (n+1,m+1)} for thesubframe n+1, transmission power for the subframe n+1 for WANtransmission is set to 23 dBm. In this case, since WAN transmissionpower should also not be affected by D2D transmission, the transmissionpower for the subframe n+1 is set to 21 dBm, and P_(CMAX_L) for D2Dtransmission subframes m and m+1 is limited to up to 18.67 dBm (that is,adjusted such that D2D subframe m≤18.67 dBm and D2D subframe m+1≤18.67dBm).

The details mentioned so far are summarized as follows.

In an environment where time synchronization between WAN transmissionand D2D transmission is not achieved (that is, an asynchronousenvironment),

(A) When D2D transmission time leads WAN transmission time

(A-i) P_(CMAX_L)=MIN {P_(CMAX_L) (n,m), P_(CMAX_L) (n,m+1)}<23 dBm

-   -   WAN transmission power=calculated transmission power (minimum        P_(CMAX_L) per slot)    -   D2D transmission power for subframes m and m+1 needs to be        adjusted not to exceed P_(Powerclass)

(A-ii) P_(CMAX_L)=MIN {P_(CMAX_L) (n,m), P_(CMAX_L) (n,m+1)}=23 dBm

When WAN transmission power <23 dBm

-   -   WAN transmission power=calculated transmission power (minimum        P_(CMAX_L) per slot)    -   D2D transmission power needs to be adjusted not to exceed        P_(Powerclass)

When WAN transmission power=23 dBm

-   -   No D2D transmission is performed

(B) When WAN transmission time leads D2D transmission time

(B-i) P_(CMAX_L)=MIN {P_(CMAX_L) (n,m−1), P_(CMAX_L) (n,m)}<23 dBm

-   -   WAN transmission power=calculated transmission power (minimum        P_(CMAX_L) per slot)    -   D2D transmission power for subframes m and m+1 needs to be        adjusted not to exceed P_(Powerclass)

(B-i) P_(CMAX_L)=MIN {P_(CMAX_L) (n,m−1), P_(CMAX_L) (n,m)}=23 dBm

When WAN transmission power <23 dBm

-   -   WAN transmission power=calculated transmission power (minimum        P_(CMAX_L) per slot)    -   D2D transmission power needs to be adjusted not to exceed        P_(Powerclass)

When WAN transmission power=23 dBm

-   -   No D2D transmission is performed

The aforementioned embodiments of the present invention can beimplemented through various means. For example, the embodiments of thepresent invention can be implemented in hardware, firmware, software,combination of them, etc. Details thereof will be described withreference to the drawing.

FIG. 22 is a block diagram illustrating a wireless communication systemto implement the present disclosure.

A BS 200 includes a processor 210, a memory 220, and a radio frequency(RF) unit 230. The memory 220 is coupled to the processor 210, andstores various pieces of information for driving the processor 210. TheRF unit 230 is coupled to the processor 210, and transmits and/orreceives a radio signal. The processor 210 implements the proposedfunctions, procedures, and/or methods. In the aforementioned embodiment,an operation of the BS may be implemented by the processor 210.

A UE 100 includes a processor 110, a memory 120, and an RF unit 130. Thememory 120 is coupled to the processor 110, and stores various pieces ofinformation for driving the processor 110. The RF unit 130 is coupled tothe processor 110, and transmits and/or receives a radio signal. Theprocessor 110 implements the proposed functions, procedures, and/ormethods.

The processor may include Application-Specific Integrated Circuits(ASICs), other chipsets, logic circuits, and/or data processors. Thememory may include Read-Only Memory (ROM), Random Access Memory (RAM),flash memory, memory cards, storage media and/or other storage devices.The RF unit may include a baseband circuit for processing a radiosignal. When the above-described embodiment is implemented in software,the above-described scheme may be implemented using a module (process orfunction) which performs the above function. The module may be stored inthe memory and executed by the processor. The memory may be disposed tothe processor internally or externally and connected to the processorusing a variety of well-known means.

In the above exemplary systems, although the methods have been describedon the basis of the flowcharts using a series of the steps or blocks,the present invention is not limited to the sequence of the steps, andsome of the steps may be performed at different sequences from theremaining steps or may be performed simultaneously with the remainingsteps. Furthermore, those skilled in the art will understand that thesteps shown in the flowcharts are not exclusive and may include othersteps or one or more steps of the flowcharts may be deleted withoutaffecting the scope of the present invention.

What is claimed is:
 1. A method for simultaneously transmitting acellular uplink signal and a proximity service (ProSe) signal, themethod performed by device and comprising: determining, by the device, atotal transmission power P_(CMAX) for the cellular uplink signal and theProSe signal; and transmitting, by the device, the cellular uplinksignal and the ProSe signal based on the determined total transmissionpower P_(CMAX), wherein the total transmission power P_(CMAX) satisfiesP_(CMAX_L)≤P_(CMAX)≤P_(CMAX_H), where P_(CMAX_L) is a lower bound andP_(CMAX_H) is an upper bound, wherein, based on (i) that the cellularuplink signal is transmitted on subframe n, (ii) that the ProSe signalis transmitted on subframe m, and (iii) that the subframe n isasynchronous with the subframe m, the subframe n is taken as areference, wherein based on (iv) that the transmission of the uplinksignal leads the transmission of the ProSe signal, the upper boundP_(CMAX_H) is determined in consideration of subframe pairs of (n, m)and (n, m−1).
 2. The method of claim 1, wherein the upper boundP_(CMAX_H) is determined by a following equation:P _(CMAX_H)=MAX {P _(CMAX_H)(n,m−1),P _(CMAX_H)(n,m)}.
 3. The method ofclaim 1, wherein the cellular uplink signal is transmitted to a basestation and the ProSe signal is transmitted to an adjacent other device.4. The method of claim 1, wherein a carrier for transmitting thecellular uplink signal is different from a carrier for transmitting theProSe signal.
 5. The method of claim 1, wherein a carrier fortransmitting the cellular uplink signal and a carrier for transmittingthe ProSe signal corresponds to an inter-band carrier aggregation.
 6. Adevice for simultaneously transmitting a cellular uplink signal and aproximity service (ProSe) signal, the device comprising: a transceiver;and a processor configured to: determine a total transmission powerP_(CMAX) for the cellular uplink signal and the ProSe signal, andcontrol the transceiver to transmit the cellular uplink signal and theProSe signal based on the determined total transmission power P_(CMAX)wherein the total transmission power P_(CMAX) satisfiesP_(CMAX_L)≤P_(CMAX)≤P_(CMAX_H), where P_(CMAX_L) is a lower bound andP_(CMAX_H) is an upper bound, wherein, based on (i) that the cellularuplink signal is transmitted on subframe n, (ii) that the ProSe signalis transmitted on subframe m, and (iii) that the subframe n isasynchronous with the subframe m, the subframe n is taken as areference, wherein based on (iv) that the transmission of the uplinksignal leads the transmission of the ProSe signal, the upper boundP_(CMAX_H) is determined in consideration of subframe pairs of (n, m)and (n, m−1).
 7. The device of claim 6, wherein the upper boundP_(CMAX_H) is determined by a following equation:P _(CMAX_H)=MAX {P _(CMAX_H)(n,m−1),P _(CMAX_H)(n,m)}.
 8. The device ofclaim 6, wherein the cellular uplink signal is transmitted to a basestation and the ProSe signal is transmitted to an adjacent other device.9. The device of claim 6, wherein a carrier for transmitting thecellular uplink signal is different from a carrier for transmitting theProSe signal.
 10. The device of claim 6, wherein a carrier fortransmitting the cellular uplink signal and a carrier for transmittingthe ProSe signal corresponds to an inter-band carrier aggregation.